githubmirror/ndctl

util/event_trace.c
298 строк6 KB
Alison Schofield
util/trace: add helpers to retrieve tep fields by type
03 окт 2024, 02:42
03 окт 2024, 02:42360b244
// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2022, Intel Corp. All rights reserved.
#include <stdio.h>
#include <errno.h>
#include <event-parse.h>
#include <json-c/json.h>
#include <util/json.h>
#include <util/util.h>
#include <util/strbuf.h>
#include <ccan/list/list.h>
#include <uuid/uuid.h>
#include <tracefs.h>
#include "event_trace.h"

#define _GNU_SOURCE
#include <string.h>

u64 trace_get_field_u64(struct tep_event *event, struct tep_record *record,
			const char *name)
{
	unsigned long long val;

	if (tep_get_field_val(NULL, event, name, record, &val, 0))
		return ULLONG_MAX;

	return val;
}

u32 trace_get_field_u32(struct tep_event *event, struct tep_record *record,
			const char *name)
{
	char *val;
	int len;

	val = tep_get_field_raw(NULL, event, name, record, &len, 0);
	if (!val)
		return UINT_MAX;

	return *(u32 *)val;
}

u8 trace_get_field_u8(struct tep_event *event, struct tep_record *record,
		      const char *name)
{
	char *val;
	int len;

	val = tep_get_field_raw(NULL, event, name, record, &len, 0);
	if (!val)
		return UCHAR_MAX;

	return *(u8 *)val;
}

static struct json_object *num_to_json(void *num, int elem_size, unsigned long flags)
{
	bool sign = flags & TEP_FIELD_IS_SIGNED;
	int64_t val = 0;

	/* special case 64 bit as the call depends on sign */
	if (elem_size == 8) {
		if (sign)
			return json_object_new_int64(*(int64_t *)num);
		else
			return util_json_new_u64(*(uint64_t *)num);
	}

	/* All others fit in a signed 64 bit */
	switch (elem_size) {
	case 1:
		if (sign)
			val = *(int8_t *)num;
		else
			val = *(uint8_t *)num;
		break;
	case 2:
		if (sign)
			val = *(int16_t *)num;
		else
			val = *(uint16_t *)num;
		break;
	case 4:
		if (sign)
			val = *(int32_t *)num;
		else
			val = *(uint32_t *)num;
		break;
	default:
		/*
		 * Odd sizes are converted in the kernel to one of the above.
		 * It is an error to see them here.
		 */
		return NULL;
	}

	return json_object_new_int64(val);
}

static int event_to_json(struct tep_event *event, struct tep_record *record,
			 struct event_ctx *ctx)
{
	struct json_object *jevent, *jobj, *jarray;
	struct tep_format_field **fields;
	struct jlist_node *jnode;
	int i, j, rc = 0;

	jnode = malloc(sizeof(*jnode));
	if (!jnode)
		return -ENOMEM;

	jevent = json_object_new_object();
	if (!jevent) {
		rc = -ENOMEM;
		goto err_jnode;
	}
	jnode->jobj = jevent;

	fields = tep_event_fields(event);
	if (!fields) {
		rc = -ENOENT;
		goto err_jevent;
	}

	jobj = json_object_new_string(event->system);
	if (!jobj) {
		rc = -ENOMEM;
		goto err_jevent;
	}
	json_object_object_add(jevent, "system", jobj);

	jobj = json_object_new_string(event->name);
	if (!jobj) {
		rc = -ENOMEM;
		goto err_jevent;
	}
	json_object_object_add(jevent, "event", jobj);

	jobj = util_json_new_u64(record->ts);
	if (!jobj) {
		rc = -ENOMEM;
		goto err_jevent;
	}
	json_object_object_add(jevent, "timestamp", jobj);

	for (i = 0; fields[i]; i++) {
		struct tep_format_field *f = fields[i];
		int len;

		/*
		 * libtraceevent differentiates arrays and strings like this:
		 * array:  TEP_FIELD_IS_[ARRAY | STRING]
		 * string: TEP_FIELD_IS_[ARRAY | STRING | DYNAMIC]
		 */
		if ((f->flags & TEP_FIELD_IS_STRING) &&
		    ((f->flags & TEP_FIELD_IS_DYNAMIC))) {
			char *str;

			str = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
			if (!str)
				continue;

			jobj = json_object_new_string(str);
			if (!jobj) {
				rc = -ENOMEM;
				goto err_jevent;
			}

			json_object_object_add(jevent, f->name, jobj);
		} else if (f->flags & TEP_FIELD_IS_ARRAY) {
			unsigned char *data;
			int chunks;

			data = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
			if (!data)
				continue;

			jarray = json_object_new_array();
			if (!jarray) {
				rc = -ENOMEM;
				goto err_jevent;
			}

			chunks = f->size / f->elementsize;
			for (j = 0; j < chunks; j++) {
				jobj = num_to_json(data, f->elementsize, f->flags);
				if (!jobj) {
					json_object_put(jarray);
					rc = -ENOMEM;
					goto err_jevent;
				}
				json_object_array_add(jarray, jobj);
				data += f->elementsize;
			}

			json_object_object_add(jevent, f->name, jarray);
		} else { /* single number */
			unsigned char *data;
			char *tmp;

			data = tep_get_field_raw(NULL, event, f->name, record, &len, 0);
			if (!data)
				continue;

			/* check to see if we have a UUID */
			tmp = strcasestr(f->type, "uuid_t");
			if (tmp) {
				char uuid[40];

				uuid_unparse(data, uuid);
				jobj = json_object_new_string(uuid);
				if (!jobj) {
					rc = -ENOMEM;
					goto err_jevent;
				}

				json_object_object_add(jevent, f->name, jobj);
				continue;
			}

			jobj = num_to_json(data, f->elementsize, f->flags);
			if (!jobj) {
				rc = -ENOMEM;
				goto err_jevent;
			}

			json_object_object_add(jevent, f->name, jobj);
		}
	}

	list_add_tail(&ctx->jlist_head, &jnode->list);
	return 0;

err_jevent:
	json_object_put(jevent);
err_jnode:
	free(jnode);
	return rc;
}

static int event_parse(struct tep_event *event, struct tep_record *record,
		       int cpu, void *ctx)
{
	struct event_ctx *event_ctx = (struct event_ctx *)ctx;

	/* Filter out all the events that the caller isn't interested in. */
	if (strcmp(event->system, event_ctx->system) != 0)
		return 0;

	if (event_ctx->event_name) {
		if (strcmp(event->name, event_ctx->event_name) != 0)
			return 0;
	}

	if (event_ctx->event_pid) {
		if (event_ctx->event_pid != tep_data_pid(event->tep, record))
			return 0;
	}

	if (event_ctx->parse_event)
		return event_ctx->parse_event(event, record, event_ctx);

	return event_to_json(event, record, event_ctx);
}

int trace_event_parse(struct tracefs_instance *inst, struct event_ctx *ectx)
{
	struct tep_handle *tep;
	int rc;

	tep = tracefs_local_events(NULL);
	if (!tep)
		return -ENOMEM;

	rc = tracefs_iterate_raw_events(tep, inst, NULL, 0, event_parse, ectx);
	tep_free(tep);
	return rc;
}

int trace_event_enable(struct tracefs_instance *inst, const char *system,
		       const char *event)
{
	int rc;

	rc = tracefs_event_enable(inst, system, event);
	if (rc == -1)
		return -errno;

	if (tracefs_trace_is_on(inst))
		return 0;

	tracefs_trace_on(inst);
	return 0;
}

int trace_event_disable(struct tracefs_instance *inst)
{
	return tracefs_trace_off(inst);
}